Dredges have been used for many years to remove submerged material from the bottom of lakes, harbors and other water areas. Reasons for engaging in dredging include deepening waterways to facilitate marine navigation, removal of bottom pollutants, recovery of bottom materials which have commercial value, and others.
Many common dredging devices are large, very expensive, and of limited use. For example, many hydraulic and pneumatic dredges will operate efficiently only in deep water, or only when excavating and removing a particular type of bottom material. Clam-shell dredges, crane buckets and other mechanical dredging devices operate efficiently only when excavating other types of bottom material, and can be expensive to operate. Most dredges require extensive ancillary systems to support the dredge, or to carry away the dredged material, or both.
In the past several years, a submergible pneumatic-hydraulic dredge pump has been offered to overcome some of these problems. However, in some forms it has met with only limited success. Operators have discovered that some forms of this pump work only in relatively deep water, and with loose material which need not be aggressively cut or separated from surrounding bottom material. In other conditions, operation of the pump has tended to become inefficient, yet efficient pump operation over a broad variety of conditions has heretofore proven expensive and difficult to control. If pump operations cannot be carefully monitored and controlled, the dredging operation can be so inefficient as to cause the pump operator serious financial difficulty.
My co-pending application, Ser. No. 067,156, filed Aug. 16, 1979, discloses a novel pneumatic-hydraulic pump dredge which can operate efficiently in deep or shallow water, and which can efficiently, precisely excavate a wide variety of materials.
It is a general object of this invention to provide an electronic control system for a pneumatic-hydraulic pump dredge and associated system generally of the type disclosed in my aforesaid copending application.
A related object is to provide such a control system which optimizes the efficiency of operation of the pneumatic-hydraulic pump dredge and associated system.
A more specific object is to provide such a control system which is capable of controlling pump dredge operation in accordance with a predetermined time cycle of operation of the pump dredge.
A related object is to provide a control system in accordance with the foregoing object wherein the time cycle of operation is further selectively controllable in accordance with the dredging conditions encountered.
Yet another object is to offer an electronic control system for a pneumatic-hydraulic pump dredge which can be constructed and operated at relatively low cost, yet which is reliable in service and rugged in design .